The research program is concerned with problems of structure and function of the nervous system. Major emphasis is on the study of peripheral and central mechanisms of sensory systems, including vision and somesthesis. Particular attention is given to specifying the topographical organization and structural and connectional features within each system. Coding of sensory information by spike discharge patterns at peripheral and central levels within each system is of special interest. Anatomical studies of regulatory pathways within the hypothalamus are also underway. The methods used are multidisciplinary. Single-unit recordings, evoked potentials and electrical stimulation are used in electrophysiological studies. Great care is taken to control the parameters of stimulation for each sensory system. Electrophysiological mapping procedures and histological identification of recording sites are important in localizing functions to structures. Computers are extensively used in collecting and analyzing data. The approach in general is comparative, employing a variety of mammals. Acute anesthetized preparations and sterile neurosurgical techniques are employed. Several anatomical methods are employed to clarify fine structural features of receptors, synapses and details of structure and connectivity. These include special histological staining procedures, quantitative neuroanatomical methods, autoradiography, histochemical tract-tracing methods and electron microscopy. BIBLIOGRAPHIC REFERENCES: Bleier, R. Supraependymal cells of hypothalamic third ventricle of Tegu lizard. A scanning electron microscopic study. J. Microscopie et Biol. Cell., 1977, in press. Bleier, R. Ultrastructure of supraependymal cells and ependyma of hypothalamic third ventricle of mouse. J. comp. Neurol., 1977, in press.